Guru Nanak travelled far and wide teaching people the message of one God who dwells in every one of God's creations and constitutes the eternal Truth.[3] He set up a unique spiritual, social, and political platform based on equality, fraternal love, goodness, and virtue.[4][5][6]

It is part of Sikh religious belief that the spirit of Guru Nanak's sanctity, divinity and religious authority descended upon each of the nine subsequent Gurus when the Guruship was devolved on to them.[7]

Nanak was born on 15 April 1469 at Rāi Bhoi Kī Talvaṇḍī (present day Nankana Sahib, Punjab, Pakistan) near Lahore.[8][9] His parents were Kalyan Chand Das Bedi, popularly shortened to Mehta Kalu, and Mata Tripta.[10] His father was the local patwari (accountant) for crop revenue in the village of Talwandi.[11] His parents were both Hindus and belonged to the merchant caste.[12]

He had one sister, Bebe Nanaki, who was five years older than he was. In 1475 she married and moved to Sultanpur. Nanak was attached to his sister and followed her to Sultanpur to live with her and her husband. At the age of around 16 years, Nanak started working under Daulat Khan Lodi, employer of Nanki's husband. This was a formative time for Nanak, as the Puratan (traditional) Janam Sakhi suggests, and in his numerous allusions to governmental structure in his hymns, most likely gained at this time.[13]

Commentaries on his life give details of his blossoming awareness from a young age. At the age of five, Nanak is said to have voiced interest in divine subjects. At age seven, his father enrolled him at the village school as was the custom.[8] Notable lore recounts that as a child Nanak astonished his teacher by describing the implicit symbolism of the first letter of the alphabet, which is an almost straight stroke in Persian or Arabic, resembling the mathematical version of one, as denoting the unity or oneness of God.[14] Other childhood accounts refer to strange and miraculous events about Nanak, such as one witnessed by Rai Bular, in which the sleeping child's head was shaded from the harsh sunlight, in one account, by the stationary shadow of a tree[15] or, in another, by a venomous cobra.[16]

On 24 September 1487 Nanak married Mata Sulakkhani, daughter of Mūl Chand and Chando Rāṇī, in the town of Batala. The couple had two sons, Sri Chand (8 September 1494 – 13 January 1629)[17] and Lakhmi Chand (12 February 1497 – 9 April 1555). Sri Chand was rebellious and disobeyed Guru Nanak's teachings; consequently, he departed from the Sikh religion and went on to become the founder of the Udasi sect of Hinduism.[18]

The earliest biographical sources on Nanak's life recognised today are the Janamsākhīs (life accounts) and the vārs (expounding verses) of the scribe Bhai Gurdas.

Gurdas, a scribe of the Gurū Granth Sahib, also wrote about Nanak's life in his vārs. Although these too were compiled some time after Nanak's time, they are less detailed than the Janamsākhīs. The Janamsākhīs recount in minute detail the circumstances of the birth of the guru.

Gyan-ratanavali attributed to Bhai Mani Singh who wrote it with the express intention of correcting heretical accounts of Guru Nanak. Bhai Mani Singh was a Sikh of Guru Gobind Singh who was approached by some Sikhs with a request that he should prepare an authentic account of Guru Nanak’s life. Bhai Mani Singh writes : Just as swimmers fix reeds in the river so that those who do not know the way may also cross, so I shall take Bhai Gurdas’s var as my basis and in accordance with it, and with the accounts that I have heard at the court of the tenth Master, I shall relate to you whatever commentary issues from my humble mind. At the end of the Janam-sakhi there is an epilogue in which it is stated that the completed work was taken to Guru Gobind Singh for his seal of approval. Guru Sahib duly signed it and commended it as a means of acquiring knowledge of Sikh belief.

One popular Janamsākhī was allegedly written by a close companion of the Guru, Bhai Bala.[19] However, the writing style and language employed have left scholars, such as Max Arthur Macauliffe, certain that they were composed after his death.[8] According to the scholars, there are good reasons to doubt the claim that the author was a close companion of Guru Nanak and accompanied him on many of his travels.[20]

Rai Bular, the local landlord and Nanak's sister Bibi Nanaki were the first people who recognised divine qualities in the boy. They encouraged and supported him to study and travel. Sikh tradition states that at around 1499, at the age of 30, he had a vision. After he failed to return from his ablutions, his clothes were found on the bank of a local stream called the Kali Bein. The townspeople assumed he had drowned in the river; Daulat Khan had the river dragged, but no body was found. Three days after disappearing, Nanak reappeared, staying silent. The next day, he spoke to pronounce:

"There is neither Hindu nor Mussulman (Muslim) so whose path shall I follow? I shall follow God's path. God is neither Hindu nor Mussulman and the path which I follow is God's."[13]

Nanak said that he had been taken to God's court. There, he was offered a cup filled with amrita (nectar) and given the command,

"This is the cup of the adoration of God's name. Drink it. I am with you. I bless you and raise you up. Whoever remembers you will enjoy my favour. Go, rejoice of my name and teach others to do so. I have bestowed the gift of my name upon you. Let this be your calling."

From this point onwards, Nanak is described in accounts as a Guru, and Sikhism was born.[21]

The main basic belief of Sikhism is no revenge, but to spread the message of kindness, and peace.[citation needed] Sikhism is one of the most recently formed religions in the world. The Sikhs, the people who follow the religion, follow the teaching of Guru Granth Sahib (the holy book for the Sikhs).

Nanak’s teachings can be found in the Sikh scripture Guru Granth Sahib, as a vast collection of revelatory verses recorded in Gurmukhi.

From these some common principles seem discernible. Firstly a supreme Godhead who although incomprehensible, manifests in all major religions, the Singular "Doer" and formless. It is described as the indestructible (undying) form.

Nanak describes the dangers of egotism (haumai- "I am") and calls upon devotees to engage in worship through the word of God. Naam implies God, the Reality, is a mystical word or formula to recite or meditate upon (shabad in Gurbani), through divine order (hukam), a guru’s instructions, [22] and singing of God’s qualities, discarding doubt in the process. Such worship must be selfless (sewa). The word of God cleanses the individual to make such worship possible. This is related to the revelation that God is the Doer and without God there is no other. Nanak warned against hypocrisy and falsehood saying that these are pervasive in humanity and that religious actions can also be in vain. It may also be said that ascetic practices are disfavoured by Nanak, who suggests remaining inwardly detached whilst living as a householder.

Through popular tradition, Nanak’s teaching is understood to be practised in three ways:

Vaṇḍ Chakkō: Sharing with others, helping those with less who are in need

Kirat Karō: Earning/making a living honestly, without exploitation or fraud

Naam Japna: Meditating on God's name to control your 5 evils to eliminate suffering and live a happy life.

Nanak put the greatest emphasis on the worship of the Word of God (Naam Japna).[22] One should follow the direction of awakened individuals (Gurmukh or God willed) rather than the mind (state of Manmukh- being led by self will)- the latter being perilous and leading only to frustration.

Reforms that occurred in the institution and both Godhead and Devotion, are seen as transcending any religious consideration or divide, as God is not separate from any individual.

Nanak crossed into Arunachal Pradesh and visited most of the part. First while going to Lhasa (Tibet) he passed through Tawang after crossing from Bhutan and entered Tibet from Samdurang Chu. He returned from Lhasa and went to the famous monastery Samye and entered Pemoshubu Menchukha in Arunachal Pradesh. He meditated for some time at this location. From Menchukha he went back to Tibet, brought the residents of Southern Tibet and got them settled in Menchukha. Thereafter through Gelling and Tuting he proceeded to Sadiya and Braham-Kund, before entering the state of Assam again.

Nanak was moved by the plight of the people of world and wanted to tell them about the "real message of God". The people of the world were confused by the conflicting message given by priests, pundits, qazis, mullahs, etc. He was determined to bring his message to the masses; so in 1499, he decided to set out on his sacred mission to spread the holy message of peace and compassion to all of mankind.

Most of his journeys were made on foot with his companion Bhai Mardana. He travelled in all four directions – North, East, West and South. The founder Sikh Guru is believed to have travelled more than 28,000 km in five major tours of the world during the period from 1500 to 1524.

In 1499 Nanak embarked on his Divine Mission and went towards east, west, north and south and visited various centres of Hindus, Muslims, Buddhists, Jainis, Sufis, Yogis and Sidhas. He met people of different religions, tribes, cultures and races. He travelled on foot with his Muslim companion named Bhai Mardana, a minstrel. His travels are called Udasis. In his first Udasi (travel), Nanak covered east of India and returned home after spending about 6 years. He started from Sultanpur in 1499 and went to his village Talwandi to meet and inform his parents about his long journey. His parents wanted their young son to provide comfort and protection for them in their old age and so they told him they would prefer it if he did not go. But he told them that the world was burning in the fire of Kalyug and that thousands and thousands were waiting for the Divine message of the Almighty for comfort, love and salvation. The Guru, therefore, told his parents, "There is a call from Heaven, I must go whither He directs me to go." Upon hearing these words, his parents agreed and gave their blessings. So Nanak started his mission and the roots of Sikhism were laid down first towards the east of India.

Nanak appointed Bhai Lehna as the successor Guru, renaming him as Guru Angad, meaning "one’s very own" or "part of you". Shortly after proclaiming Bhai Lehna as his successor, Guru Nanak died on 22 September 1539 in Kartarpur, at the age of 70.[24]

^Singh, Khushwant (2006). The Illustrated History of the Sikhs. India: Oxford University Press. pp. 12–13. ISBN0-19-567747-1. Also, according to the Purātan Janamsākhī (the birth stories of Guru Nanak).